In a vehicle, such as an automotive vehicle having an internal combustion engine, the temperature of the engine and the temperature of other vehicle components needs to be managed. Typically, known cooling systems for internal combustion engines comprise a pump driven directly by the engine itself. The pump provides a supply of coolant to the engine and to other components of the vehicle. A radiator is typically used to cool the coolant. In this way, as coolant is recirculated by the pump, the coolant continuously cools the engine. The pump and cooling system need to be of a sufficient capacity such that when the engine is operating at a high temperature, the cooling system can nevertheless cool the engine to prevent damage, fatigue or failure of the engine or its components that can be caused if the engine is operated at too high a temperature. A vehicle engine may operate at a high temperature, for example due to the vehicle working hard by travelling uphill, towing a heavy load and/or travelling in a hot climate. Vehicles are typically provided with a cooling system wherein the pump is constantly operated at its maximum output, irrespective of the actual temperature of the engine, the climate the vehicle is in, or the current and changing workload placed on the engine of the vehicle.
However it is not necessary, or indeed beneficial, to constantly provide the maximum cooling of the vehicle engine. In many driving scenarios, little or even no cooling is actually required, but the pump is nevertheless constantly driven and is constantly consuming energy needlessly. Furthermore, it is desirable for optimum fuel efficiency, and to minimise wear on the components of an engine, for the engine to actually operate when it is warm and not too cold. Of particular importance is the temperature of lubricant about the pistons and piston rings. Operation of the engine when the lubricant is below an optimum temperature may have a deleterious effect on the engine. A cooling system operational automatically with the engine and at a constant maximum output, therefore reduces the fuel efficiency of the engine, as well as potentially reducing the service life of the engine or other components. It is desirable to improve the fuel efficiency of vehicles.
The present invention seeks to at least mitigate against or otherwise avoid the problems associated with the prior art by providing an improved method of controlling a cooling system for a vehicle.